There's no doubt Terrell Sinkfield proved he was fast. But just how fast?

According to Fox Sports North, the Northern Iowa wide receiver prospect for the 2013 NFL draft ran a 40-yard dash in an incredible 4.19 seconds at the University of Minnesota's pro day on Monday.

Sinkfield was a high school track star in Minnesota but had modest football production for UNI. But he certainly believed he ran that fast—five-hundredths of a second faster than what Titans running back Chris Johnson (4.24) posted at the 2008 Combine.

“That was the expectation, really," Sinkfield told Fox Sports North. "Aim big. I was trying to get that 4.1."

But not so fast, according to Scott Studwell, the Vikings' college scouting director who was in attendance. The St. Paul Pioneer Press reports Studwell had Sinkfield clocked between 4.3 and 4.4 seconds at best on his three attempts. FSN had him at 4.27 and 4.41 on his other two attempts.

To put Sinkfield's run into perspective, consider this: the splits on Usain Bolt's 2009 record-setting 100-meter dash indicate he covered the first 40 yards in about 4.24 seconds. There are many variables to consider—not limited to shoes, surface, training and the average created when converting a meter split to yards—but the takeaway suggests Sinkfield might be better off pursuing an Olympic career.

No matter his unofficial official time, Sinkfield can fly, and that will make NFL scouts take notice of a previously little-known small-school receiver. Check out his 40-yard dash here: